Αν το τσιρότο βραχεί, πρέπει να το αλλάξεις αμέσως.

Yes. Το τσιρότο is the everyday word for an adhesive bandage, like a Band-Aid or plaster.

A few notes:

• It is a neuter noun.
• Its basic form is το τσιρότο.
• In medical or very formal language, you might hear more technical terms, but τσιρότο is the normal everyday word.

Αν means if.

It introduces a condition:

• Αν το τσιρότο βραχεί = If the bandage gets wet
• πρέπει να το αλλάξεις αμέσως = you must change it immediately

So the whole sentence has the classic if ..., then ... structure.

Because τσιρότο is a neuter singular noun, and neuter singular nouns usually take the article το.

So:

• το τσιρότο = the bandage / the plaster

Here το τσιρότο is the subject of βραχεί.
For neuter nouns, the nominative and accusative singular often look the same, so το is the expected form.

They are doing two different jobs.

1. το τσιρότο
   Here το is the article = the

2. να το αλλάξεις
   Here το is the object pronoun = it

So:

• το τσιρότο = the bandage
• το αλλάξεις = change it

English also does this in a way:

• If the bandage gets wet, you must change it immediately.

Βραχεί is the form used here to mean gets wet / becomes wet.

It comes from the verb βρέχω / βρέχομαι (to wet / to get wet). In this sentence, Greek uses the form that is typical after αν when talking about a possible future event:

• Αν το τσιρότο βραχεί = If the bandage gets wet

This form focuses on the event as a single complete occurrence: the bandage ends up wet.

A useful rough way to feel it is:

• if it should get wet
• more natural English: if it gets wet

Because Greek normally does not use θα after αν in this kind of condition.

So Greek says:

• Αν το τσιρότο βραχεί
  not
• Αν το τσιρότο θα βραχεί

This is similar to English, where we usually say:

• If it gets wet not normally
• If it will get wet

So the Greek structure is very natural.

Πρέπει means something like:

• it is necessary
• one must
• must / should / need to

In this sentence, it is best understood as:

• you must or
• you need to

A key grammar point: πρέπει is impersonal. It does not change to match the person.

So:

• πρέπει να φύγω = I must leave
• πρέπει να φύγεις = you must leave
• πρέπει να φύγουν = they must leave

The word πρέπει stays the same.

Because να το αλλάξεις presents the action as one complete action: change it.

• να το αλλάξεις = change it once / replace it
• να το αλλάζεις = be changing it / change it regularly or repeatedly

In this sentence, the meaning is:

• if the bandage gets wet, replace it right away

So the complete, one-time action is the natural choice:

• πρέπει να το αλλάξεις αμέσως

Greek often leaves subject pronouns out because the verb ending already shows the person.

Here:

• αλλάξεις = you change / you should change
  more literally, it contains the idea of you inside the ending

So Greek does not need to say εσύ.

If you want to emphasize you, you could say:

• πρέπει να το αλλάξεις εσύ

But in a normal sentence, leaving εσύ out is completely standard.

Αλλάξεις is second person singular, so it means you when speaking to one person informally.

So this sentence is addressed to:

• one person
• in the normal singular you form

If you were speaking to more than one person, or using the polite/formal plural form, you would say:

• πρέπει να το αλλάξετε αμέσως

Αμέσως means:

• immediately
• right away

It is placed at the end here because that is a very natural position in Greek:

• πρέπει να το αλλάξεις αμέσως

That word order sounds neutral and natural. Greek word order is fairly flexible, but this version is the most straightforward:

• If the bandage gets wet, you must change it immediately.

Yes, to some extent.

For example, you could also say:

• Πρέπει να το αλλάξεις αμέσως, αν το τσιρότο βραχεί.

That still means the same thing.

But the original order is very natural because it gives the condition first:

• Αν το τσιρότο βραχεί, ... then the result/instruction:
• πρέπει να το αλλάξεις αμέσως

Also notice that the object pronoun το normally comes before the verb here:

• να το αλλάξεις

That is the normal placement in this kind of sentence.